So it just looks like they do invisible stairs until they're into air. Although do they just float up then go

Like an Osa-Yukkuri, of course.

"Thing is delivering papers"

Okay.

It flies according to Osa-Yukkuri Logic.

Aya flies. Therefore AyaYuku flies.

LittleFuzzy said:

It flies according to Osa-Yukkuri Logic.

Aya flies. Therefore AyaYuku flies.

But Osa-Akyuu walks up Walls

Akyuu doesn't walk up walls

Zelinkokitsune said:
But Osa-Akyuu walks up Walls

Akyuu doesn't walk up walls

It's not, "the Osa-Yukkuri can do it, if the Gensokyo resident on whom they're based can do it".

It's, "the Osa-Yukkuri can do it, if there is a logical-sounding argument to be made for why. Even if (or especially if) the argument falls apart under examination."

Example:

To make a chimney, you need to use tools.
A scissors is a tool.
Therefore, Osa-Keine can use scissors to make a chimney.

LittleFuzzy said:

To make a chimney, you need to use tools.
A scissors is a tool.
Therefore, Osa-Keine can use scissors to make a chimney.

best logical explanation i ever seen for something that was suppose to be illogical